Mcl-1 (myeloid cell leukemia-1) is a 37 kD Bcl-2 related protein found in mitochondrial and non-mitochondrial membranes that dimerizes with Bax. Mcl-1 has been shown to act as a survival factor for hematopoietic cells and contribute to the STAT-dependent protection of neutrophils against apoptosis. Mcl-1 is increased by PMA, GM-CSF, M-CSF, IL-1beta, IL-3, and IL-6 in hematopoietic cells. This protein is decreased following growth factor withdrawal. Mcl-1 is modified by JNK phosphorylation. The Poly6136 antibody has been shown to recognize mouse Mcl-1 and has been shown to be useful for Western blotting.